Packaging lines in plants which handle food and other consumer products have, in the past, used packaging machines which fill open packages as they move past a package filling station. These machines are suitable for certain products, either processed or unprocessed, especially those that are in forms which assure that the products do not adhere to adjacent surfaces by surface tension or other forces or at least can be readily scraped from such surfaces. Typical of the products handled by such machines are powders, such as rochelle salts for medicinal use, butter, margarine, lard, candy, soap, plastics, dough, meat balls, ice cream, and the like.
A number of references have disclosed the packaging of food and other products, among which are the following prior U.S. Pats. Nos. 1,091,568; 2,467,268; 2,653,430; 2,823,499; 3,125,039; 3,126,683; 3,768,228; 3,889,448.
For the most part, these patents disclose machines which are complicated in construction and are not disclosed as being suitable for use in packaging of wet, sticky food products which agglomerate when blanched or pre-cooked.
Some attempt has been made to package blanched or pre-cooked vegetables, but these have been generally unsuccessful with certain foods, including leafy, sticky, wet vegetables, such as spinach, mixed greens, chopped broccoli, rubarb and squash. A main reason why problems arise with a vegetable of this type is because the vegetable has a wet, sticky consistency, causing it to ball up or agglomerate when it is being packaged in unit weights or volumes. As the vegetable is dropped into a package, it forms a mound in the center of the mass deposited in the package. This shape makes the corners of the package contain less product than they should, thereby leaving spaces for accumulation of moisture. When the package is moved through a freezing station, this moisture is frozen, leaving a residue which is unsightly and uninviting to the consumer when the package is opened.
Another drawback of the techniques of the prior art for filling packages is the fact that they do not uniformly fill packages time after time with the same basic weight or volume of vegetables of the type described. Some packages may be overweight, some may be underweight, and some may be at the proper weight. However, the probability of having uniformity in weight is relatively low because the product is hard to handle due to its sticky, wet consistency. This causes rejection of many packages and the slowdown of the packaging line, resulting in increased labor and machine operating costs. In lieu of such machine operation, manual filling of the packages has been used but, since labor costs are relatively high, this is an expensive approach to the food packaging problem.
A need, therefore, has arisen for an improved apparatus and method for handling a food product of the wet, sticky, pre-cooked type to render the packaging of such food products faster and cleaner, yet provide uniformity in the filling of packages as the packages move in great numbers along a conveyor line toward a freezing station.